I think for me, the issue isn't that LeBron is dancing, it is that the look on his face while dancing is very much the same "look at how awesome I am" look LeBron gave during his intro to the Heat fans: (2:50) http://www.youtube.com/watch?v=FmwJipHdqpA

LeBron is able to communicate his douche baggery through his body language and his facial expressions. Other guys know how to dance and make it look like they are having fun, but LeBron's dancing/facial expression was more of a "look at me" than a "this is fun." Btw, Dwight was just as guilty at the all-star game, but seems to be getting a pass, likely because he doesn't have as big of a history of this shit.